#ifdef GL_ES
precision mediump float;
#endif

uniform float u_time;
uniform vec2 u_resolution;
uniform vec2 u_mouse;


void main(){
    vec2 st = gl_FragCoord.xy / u_resolution;
    float pct = length(st - vec2(0.5)) * 20.0;
    pct = mod(pct,1.0 - 0.1);
    vec3 color = vec3(pct);
    gl_FragColor = vec4(color,1.);
    
}